Transient wall temperature response during liquid nitrogen nucleate pool boiling: CFD analysis and experimental validation

Abstract

The phenomenon of heat transfer by phase change (liquid/vapor) is used for wall cooling in a number of fields, including power generation, renewable energy and nuclear reactors. This choice is explained by its ability to evacuate high surface heat fluxes at relatively low wall temperatures. In most cases, cooling systems are designed based on steady-state experimental studies. However, during start-up phases or when sudden flow variations occur in cooling systems, surface heat fluxes or wall temperatures may vary considerably from values determined under stationary conditions. Boiling under transient conditions, therefore, reveals a number of peculiarities whose understanding will contribute to fundamental knowledge of this phenomenon. This paper focuses on the numerical study of the transient nucleate pool boiling heat transfer due to the horizontal immersion of a brass ribbon in liquid nitrogen. In addition, the superheat nucleate boiling and the critical heat flux (CHF), which is a critical factor for system safety, has been specifically analyzed. Finally, these numerical results obtained based on a CFD analysis using COMSOL Multiphysics software were compared to experimental data and the percentage error was no more than 13%.